Power limiting device



Dec. 15, 1.931. R. H. MARRIOTT 1,836,379

I POWER LIMITING DEVICE Filed July 7, 1928 CC v 9g & E I?! g M I 2: 0 0LI m 3 [I w 3 Cr ADJU STABLE ADJU STABLE DISCHARGE GAP DISCHARGE CAPINVENTOR Penman. 15, 193i UNITED STATES HENRY MARRIOTT, BROOKLYN, NEW"YORK rowm-Lmrrme nmca Application filed July 7, 1928. Serial Ho.291,092.

This invention relates to power limiting devices. Its .object' is tolimit the power which may be transferred from a 'source to a subsequentcircuit, that is, to insure that the power in excess of a predeterminedamount shall be materially reduced in the transferring of power from thesource to the subsequerit circuit. This object is accomplished by makinguse of the fact that 10 air and other gases are insulators at lowervoltages," lose their insulating quality at higher voltages and regaintheir insulating quality when the appliedvoltage falls below a criticalvalue. (When the available power is great enough to provide a voltageand cur rent suflicient tobreak down the insulating quality of apracticable thickness ofair orother gas it'is then practicable toutilize the above mentioned characteristic of air and other gases toshunt off and to neutralize excess power. 1 v This invention appliesmore particularly to the audio frequency circuits of radioreceivingsystems in which sufiicient amplified "power is now commonlydeveloped by undesired disturbances to alone or in addition.

7 to the desired broadcasted power produce voltages that will breakdownthe insulating quality of practicable thicknesses of air or 39 othergases.

As a practical illustration, lightning disduced by the loud speaker of aradio broadcast receiver, that are very much louder than the maximumvolume of the music which is being reproduced by the loud speaker. Suchclicks and crashes when of short duration and when they are reduced involume to that of the maximum volume of the music, in- 9 terfere verymuch, les's'than-th'e do when they are several times as loud as te-music.

The specific purpose of this invention is to providea means for limitingthe power -de-.

livered to the loud speaker to -'a power. equal being rece ed. Th' makesit desirable that the power limiting device be; adjustable for.

to the maximum satisfactory power obtainable from the par 'cularbroadcast that is' var ing the applied voltage, the length ofthe patthrough the gas or the gas pressure, or

by combining two or more of these variables.

Therefore, this application describes a power limiting device applicablefor use in broad? cast reception including means for varying the pointof power limltation to conform'to the variations of normal poweravailable from broadcasting programs Fig. 1 is a schemat1c diagram of myinvention.

Fig. 2 is a schematic wiring diagram of a modified form of my invention.

Fi n'3 is another schematic diagram of a modified form of my invention.

Fig. 4; is a detailed view of adjustable gap.

Fig. 5 illustrates a type of low pressure gas tube gap embodied in mylIlVEl'ltlOD.

Fig. 6 illustrates in modified form a low pressure type of gas tubegap'erhbodied in my invention.

Fig. 7 illustrates in modified form a multiple electrode lo n pressuregas tube gap embodied in my invention.

open spark gap embodied in my invention.

My invention will be more clearly understood when-the followingdescription is read with reference to'the several views in theaccompanying drawlngs. charges cause GIICkS and crashes to be proquencytransformerand 2 and 3 represent the split secondary of thattransformer. The half of the secondary marked 2 is connected to therimary 4 of a second audio frequency transormer, the secondary 6 ofwhich is connected to a-loud speaker 7. The half. of the secondarymarked, 3 is connected to 4 through the common c onnection'of 2 and. 3and at its opposite end to one side of the adjustable discharge gap 5.The other side of this gap is connected to the upper end-of thesecondary winding 2. The secondary winding comprising equal arts 2 and 3is a continuous windsucht at with the adjustable gap closed to produce ashort circuit, 2and 3 are in opposition whereby the potential of 2neutralizes the potential of 3.to such anextentthat little nation of alow pressure gas tube gap and or no current flows through the primary 4.The ratio of the turns in the secondary'2 and 3 to the turns in theprimary 1 is such that the stepped up potential is capable of jumpingthe gap 5 when the strength is above normal loud speaker Volume. If thebroadcast is .not very loud and the clicks and crashes due to variousforms of so-called static are louder; the adjustable gap is closed to apoint a little too wide to allow voltages generated by the broadcast tojump the gap. The'voltages generated by the static disturbances aloneor'added to the broadcast voltages, break down the gap and neutralizethe potential across the primary 4 by an amount approximately equal totheaniount the potential of secondry 2 has been raised by the staticabove the normal broadcast voltage. This reduces the effect of clicksand crashes so they are practically no louderthan the broadcast. Largeamplitude clicks of short duration may be thus reduced from distressmgloudness to belng of no particular consequence among musical notes oflonger duration. The impedance of the primary winding- 4 is made aboutequal to the impedence of one half of the split winding 2 and 3 or equalto 2 or 3.

Figure 2 is similar to Figure 1. except that a variable resistance 8 isprovided and the speaker 7 is substituted for the primary winding. Byproviding the variable resistance with the discharge gap connectible topoints 10 or 11, finer adjustments of relative impedances are possible.By 'making the impedal ice of the winding of the loud speakerapproximately equal to 2 it is not necessary to use a transformer as isshown at 4 and 6 in Figure 1.

In Figure 3 the discharge gap is not adjustable but the voltageimpressed on the gap is made adjustable by making the secondary halves 2and 3 variable as to the number of turns in use. In this case 4 mayrepresent the rimary of a transformer such as 4 and 6 in igure 1 on thewinding of a loud speaker; however, 4 is preferably adjustable as tonumber of turns in use so that the impedence of 4 may be madeapproximately equal to the impedence of 2.

Figure 4 shows a simple form of an adjustable gap 5 the length of whichis varied by operating the threaded portion 8 with the head 10 throughthe fixed support 9 to bring the point nearer to or farther from thefixed point 6 supported by 14. The support 14.

being connected to a terminal 12 and the support 9 being connected to aterminal 13,

all. parts being of conducting material except the base 11 and the screwhead 10 which are of insulating material. 7

Figure 5 illustrates another form of variable discharge path comprisinga series of low' pressure gas tubes of a character; similar to Geislertubes arranged to use one or two or more in series. 6 represents theinsulating and vacuum retaining wall of the tubes. 7 and 8 represent theelectrodes and 5 represents the gaps between electrodes. The tubes a, band c are connected in series with the free electrode of the end tube aconnected to a terminal 12. The connection between tube a and tube 6 isconnected to a switch contact 9. The connection between the tube b andthe tube a being connected to a switch terminal 10. The free electrodeof the tube a is connected to a. switch terminal 11.

Switch arm 14 is connected to a terminal 13 and can be brought intocontact with the switch terminals 9, 10 and 11. All three tubes may beadjusted to break down at the same voltage or by using difierent lengthsof gaps or different gas pressure or both, or they may be adjusted tobreak down at different voltages.

Figure 6 shows a low pressure gas tube wherein the length of the gap maybe adjusted by turning the tube. 6 is the envelope, 12 and 13 areterminals connected to electrodes 8 and 7 respectively. Electrode 7 ishinged at 1 so that if the-tube is rotated 90 to the left about 1 theloose portion of electrode 7 will take the position shown in the dottedline, thereby widening the gap 5 for every position between the verticaland horizontal positions of the loose portion of 7. As the break downdifferent break down voltages.

Figure 7 shows a tube in-which several electrodes 8 are sealed in atdifferent dis tances from electrode 7 and connected to switch points 9,10 and 11. Switch arm, 14 is arranged to make contact with 9, 10 or 11and is connected to terminal 13 while electrode 7 is connected toterminal 12.

In Figure 8 a low gas pressure tube is shown in series with anadjustable spark gap in normal airpressure. 6 is the envelope of thetube, 7 and 8 the electrodes and 5 the discharge gap. 17 is the fixedelectrode of the gap, 18 is the adjustable electrode and 15 is the gapof an adjustable gap similar to that described in Figure 4. The ordinarygap in air produces a somewhat rougher sound in cutting off peaks thandoes the gap in reduced gas pressure while thegap in air is the moresimple from the standpoint of adjustability. Using the two in seriesgives practically the range of adjustability of the gap in air and lessroughness of sound than is produced by the gap in air alone. Also thepermanent gap in gas prevents the short-circuiting of the discharge gapsystem.

I claim: 1

1. A power limiting device comprising a transformer having a primary anda pair of secondary windings, a spark gap adapted to be broken down byan excess potential,

How of current in one of said secondary wind-V ings in opposition to theflow of current in the other winding, said spark gap comprising a gastube in which the distance between the electrodes may be varied byrevolving the tube.

3. A power limiting device comprising a transformer having an inputprimary winding and an output secondary winding magnetically coupledthereto, alow pressure gas tube capable of passing a current when agivwhen current flows through said spark ap. Signed at New York, in thecounty of ew York and State of New York, this twentysixth da of June, A.D. 1928.

' fiOBERT HENRY MARRIOTT.-

en potential is exceeded, said tube having its electrodes connectedrespectively to one end of and the middle of said secondary winding.

4. In aradio receiving system,- an audio frequency transformer having aprimary winding and a split-secondary winding, a second audiofrequencytransformer, one end of the primary of which is connected to saidsecondary by a'conductor having uniform conductivityQand the same end ofsaid primary, of said second transformer being con nected to theopposite end of said secondary of the first mentioned transformer by ashunt containing an adjustable spark gap and the opposite end of saidprimary being connected ,to the midpoint of said secondary of said firstmentioned transformer.

5. A power limiting device comprising a transformer having a primarywinding and two opposed secondary windings, one of said secondarywindings being connected at all times in current conducting relation to'output terminals and the other of said windings a being connected tothe same output terminals by a circuit containing a spark gap, saidsparkgap preventing flow of current-through said second winding before apredetermined potential is exceeded. V

6. A power llmltmg device comprising a transformer having a primarywinding, and

secondary winding to split the same into two equal parts, one end ofsaid secondary windinglbeing connectedto one side of the input c1rcu1tof a translating device, the other 'end of said secondary winding beingconnected through a spark gap to the same side of the input circuit ofsaid translating device, and said midpoint conductor being connected tothe other side of the input circuit of said translating device, wherebysaid secondary is a continuous secondary winding, an output conductorconnected'to a midpoint of said split into two portions opposing J eachother I

